We must unravel Jupiter’s cryptic origin story to find ET

Above all, astrobiologists want one thing: to find evidence of extraterrestrial life. This is of course easier said than done. Space is huge. Stars, planets and moons are innumerable. Our probes are few and far between, and our telescopes can only see so far and with so much accuracy.

But it helps to narrow the search. To that end, a team of astrobiologists led by Artem Aguichine of the University of Aix-Marseille in France turned their attention to Jupiter, one of the strangest planets in our solar system. “Understanding planet formation is key to predicting planetary habitability and searching for extraterrestrial life, which is the main goal of astrobiology,” Aguichine told The Daily Beast. Aguichine’s new study recently peer-reviewed and submitted The Planetary Science Journalappeared online on May 2nd.

Jupiter’s atmosphere is unlikely to support life — at least not life as we currently know it. So it stands to reason that planets how Jupiter shouldn’t support life either. If we can figure out where the planet came from and how it became so uninhabitable, perhaps in our search for extraterrestrials we could rule out some of the 5,000 or so nearby “exoplanets” in star systems other than our own.

No one is quite sure how the fifth planet formed from the sun and how it got to where it is. The oldest and largest of our seven neighboring planets is mostly gas by volume — with a churning hydrogen and helium atmosphere 2,000 miles thick and riddled with clouds laced with ammonia crystals. It’s an atmosphere most astrobiologists believe to be inhospitable to living things.

In the past 25 years, only two probes have paid a close visit to the massive gas planet. NASA’s Galileo probe between 1995 and 2003, and the Juno mission from 2016 to 2018. Using data from these probes, as well as other flyby missions, Aguichine and his team built a sophisticated computer model that they hope will represent the Jovian formation from about 4.6 billion years ago – and also record its movement through the solar system.

The model combines many findings from various space sciences. There are rules for how ice and steam behave in space, especially in close proximity to a star. There are also rules for how primeval space rocks clump together to form the cores of planets, and how these rocky cores collect gas from nebulae that pass through them before settling, creating magnetic fields and forming an adult planet.

By applying their model to the data from Galileo and Juno, Augichine and co. concluded that Jupiter was possibly a restless Planet in its youth – moving toward and then away from the Sun while gradually morphing into the hostile gas monster we know today.

If the team can confirm its conclusions through better and better telescopes and future probes, they can apply the same model to other large, gas-filled planets scattered across the galaxy. If these planets are aligned with Jupiter, we may be able to rule them out as a possible home for ET.

NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gil

Despite its mass, the gas giant is light-footed, so to speak. The consensus is that the planet began as a rocky core hundreds of millions of miles from the sun. Fueled by a nebula of gas that once surrounded the star and Saturn’s core, which began forming shortly after Jupiter, the rock that would become the planet moved closer and closer to the sun over a period of millions of years . Astronomers call it migration. After growing to its bloated size, the planet eventually settled into its current orbit, 470 million miles from the Sun.

Scientists agree that Jupiter’s passage through the solar system may have been one of the defining events in the formation of everything else around us. It swept aside countless asteroids, scooping out much of the Sun’s nebula and leaving a trail of rocky debris that eventually merged into smaller planets, including Earth. “The big implication is that Jupiter, as the ‘king of the planets,’ played the dominant role in shaping the appearance of our solar system,” Christoph Burkhardt, an astronomer at the University of Munster’s Institute of Planetology, told The Daily Beast.

However, this is where the consensus ends. “It’s extremely difficult to distinguish between different formation scenarios,” Ravit Helled, a planetary scientist at the University of Zurich, told The Daily Beast. Another popular theory holds that Jupiter is approximately 1.7 billion miles from the Sun before slowly closing in distance.

Aguichine and his team disagree with this theory. Their model supports a more elaborate idea called “grand tack,” a term that refers to a sailing maneuver known as a tack, in which a boat changes direction when sailing into the wind. In this origin story, the planet formed somewhere between 300 and 450 million miles from the Sun and migrated up to a few hundred million miles closer over a period of millions of years.

There Saturn – a younger and faster planet – caught up with Jupiter. Pulling together with the swelling force of their respective gravities, the two giant planets push each other away from the sun. They both migrated back into orbit where we now find them.

NASA/JPL-Caltech/SwRI/MSSS

“Our results are compatible with some theories where Jupiter has not undergone strong migration,” Aguichine said. The main reason for this: The planet has many heavy elements in its atmosphere in addition to hydrogen and helium, which suggests that it was born much closer to home. After all, these elements had to come from somewhere. The popular theory is that they were concentrated in the nebula that once shrouded the sun before planets like Jupiter picked them up.

According to Aguichine’s model, if the gas giant were born nearly 2 billion miles from the Sun, it would have fewer heavy elements because there were never many heavy elements that far out. Therefore, Aguichine and co. claim that Jupiter formed much closer to the Sun — a starting position consistent with Grand Tack theory.

This is not established science. Aguichine and his co-authors emphasized that we need more data before concluding that Jupiter made a reverse run near the Sun in its youth. “Further developments in the modeling of Jupiter’s deep interior will provide better knowledge of its internal structure and composition, which will help distinguish between different formation scenarios,” they wrote.

It would help to take a closer look at the data from the Juno probe, Jonathan Lunine, chair of the astronomy department at Cornell University and one of Aguichine’s co-authors, told The Daily Beast. We could also send a new probe to Saturn, which may have followed a path similar to Jupiter’s.

In the meantime, there’s no harm in comparing Jupiter to distant exoplanets. We might find some that look like they were formed by needles back and forth around their stars, just as Jupiter might have done. This could potentially eliminate some of these planets from our search for extraterrestrial life.

Luckily, we have just the thing: NASA’s new $10 billion James Webb Space Telescope, launched in 2021 after decades of development. “JWST will help us here with detailed measurements of the composition of atmospheres of giant planets around other stars,” said Lunine.

The new telescope has just started capturing its first super-sharp images of distant planets. Planets that could be just as strange and hostile to life as Jupiter.